Head pressure relief assembly

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. § 119(e) of U.S. provisional patent Ser. No. 60/368,882, entitled: Head Pressure Relief Assembly, filed on Mar. 29, 2002, and U.S. provisional patent Ser. No. 60/369,536, entitled: Head Pressure Relief Assembly, filed on Apr. 2, 2002. U.S. provisional patent Ser. Nos. 60/368,882 and 60/369,536 are herein incorporated by reference in their entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to the field of air compressors having a compressor including a head assembly capable of porting a gas such as air under pressure and more particularly to a head pressure relief apparatus for the head assembly of such an air compressor.

BACKGROUND ART

Air compressors used to provide compressed air for operating air powered tools such as nailing tools, spray painting tools, inflation chucks, and the like typically include an engine or motor coupled to a compressor and mounted to a compressed air storage tank. The compressor includes a head assembly, connecting tubing and a check valve that supplies atmospheric air to the piston assembly and delivers compressed air from the piston assembly to the compressed air storage tank.

Before the compressor is started, it is desirable to relieve pressure from the exhaust cavity of the head assembly to reduce the load placed on the engine or motor. Consequently, air compressors usually include a valve, commonly referred to as the pressure switch unloader valve, and a pressure relief tube, which allow air to be vented from the head assembly to the atmosphere when the compressor is turned off.

In many applications, it is desirable to simplify the design of an air compressor in order to realize savings in manufacturing costs, maintenance costs, weight, and the like. In such applications, it may be advantageous to reduce the complexity of the air compressor by eliminating the pressure switch unloader and pressure relief tube. Consequently, it would be advantageous to provide a mechanism by which pressure may be vented from the head assembly. It would further be desirable to vent this pressure when the compressor is not running, but to prevent such venting when the compressor is running.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a head pressure relief assembly for relieving pressure in the head assembly of a compressor. In one exemplary embodiment, the head pressure relief assembly includes an exhaust valve post formed in the head assembly and an exhaust valve assembly. An aperture is formed through the exhaust valve post for venting the head assembly before the start of the compressor assembly. The exhaust valve assembly is capable of engaging the exhaust valve post to close the aperture at least partially for preventing flow from the head assembly through the aperture during the compression stroke of the compressor assembly piston. In another exemplary embodiment, the head pressure relief assembly may include one or more small holes in the head assembly, connecting tubing, and check valve, through which compressed air in the exhaust cavity of the head assembly may vent.

It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:

<figref idref="DRAWINGS">FIG. 1</figref> is a partial isometric view illustrating an air compressor including a compressor having a head assembly employing a head pressure relief assembly in accordance with exemplary embodiments of the present invention;

<figref idref="DRAWINGS">FIG. 2</figref> is an exploded isometric view showing the head assembly shown in <figref idref="DRAWINGS">FIG. 1</figref>, further illustrating a head pressure relief assembly in accordance with an exemplary embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 3</figref> is a cross-sectional side elevation view of the head assembly shown in <figref idref="DRAWINGS">FIG. 2</figref>, illustrating exemplary operation of the head pressure relief assembly, wherein the exhaust valve assembly is closed;

<figref idref="DRAWINGS">FIG. 4</figref> is a cross-sectional side elevation view of the head assembly shown in <figref idref="DRAWINGS">FIG. 2</figref>, illustrating exemplary operation of the head pressure relief assembly, wherein the exhaust valve assembly is open during a compression stroke of the compressor piston; and

<figref idref="DRAWINGS">FIG. 5</figref> is an isometric view illustrating the flapper valve of the head pressure relief assembly shown in <figref idref="DRAWINGS">FIGS. 2</figref>, <b>3</b> and <b>4</b>.

<figref idref="DRAWINGS">FIG. 6</figref> is an exploded isometric view showing the head assembly shown in <figref idref="DRAWINGS">FIG. 1</figref>, further illustrating a head pressure relief assembly in accordance with another exemplary embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 7</figref> is a cross-sectional side elevation view of the head assembly shown in FIG. <b>6</b>.

<figref idref="DRAWINGS">FIG. 8</figref> is a partial isometric view illustrating an air compressor including a compressor having a head assembly, employing a head pressure relief assembly including a hole in a connecting tube in accordance with an exemplary embodiment of the present invention;

<figref idref="DRAWINGS">FIG. 9</figref> is a partial isometric view illustrating an air compressor including a compressor having a head assembly, employing a head pressure relief assembly including a hole in a check valve in accordance with an exemplary embodiment of the present invention;

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a head pressure relief assembly for relieving pressure in the head assembly of a compressor in an air compressor. In one exemplary embodiment, the head pressure relief assembly includes an exhaust valve post formed in the head assembly and an exhaust valve assembly. An aperture is formed through the exhaust valve post for venting the head assembly during start of the compressor assembly. The exhaust valve assembly is comprised of a flapper valve capable of engaging the exhaust valve post to at least partially close the aperture for preventing flow from the head assembly through the aperture during the compression stroke of the compressor assembly piston. In another exemplary embodiment, the head pressure relief assembly may include one or more small holes in the head assembly, connecting tubing, and check valve, through which compressed air in the exhaust cavity of the head assembly may vent. Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.

<figref idref="DRAWINGS">FIG. 1</figref> depicts an air compressor <b>100</b> in accordance with an exemplary embodiment of the present invention. The air compressor <b>100</b> includes a compressor assembly <b>102</b> mounted to a compressed air storage tank <b>104</b>. The compressed air storage tank <b>104</b> provides a reservoir or receiver for storing air under pressure. A port (often referred to as a “spud”) is provided in the compressed air storage tank <b>104</b> to which a pressure manifold or pipe <b>106</b> is fitted allowing compressed air to be drawn from the tank <b>104</b> for powering air powered tools such as nailing tools, socket driving tools, material shaping tools, sanding tools, spray painting tools, tire inflation chucks, and the like.

A pressure switch assembly <b>108</b> is mounted to the pressure manifold <b>106</b> for regulating pressure within the compressed air storage tank <b>104</b> by alternately starting and stopping the compressor assembly <b>102</b> to periodically replenish the supply of air in the tank <b>104</b>. When pressure within the tank <b>104</b> reaches a preset low pressure point, or “kick-in pressure”, the pressure switch assembly <b>108</b> starts the compressor <b>102</b> to re-pressurize the tank <b>104</b>. As the pressure within the tank <b>104</b> reaches a preset high pressure point, or “kick-out pressure”, the pressure switch assembly <b>108</b> stops the compressor <b>102</b> to prevent over-pressurization of the tank <b>104</b>. In this manner, the pressure of the compressed air in the compressed air storage tank <b>104</b> is maintained within a range generally suitable for powering one or more air-powered tools.

The compressor assembly <b>102</b> includes an engine or motor <b>110</b> and a compressor <b>112</b> comprised of a housing <b>114</b> having a cylinder formed therein in which a piston assembly is disposed. The piston assembly is journaled to a crankshaft which couples the piston assembly to the engine or motor <b>110</b> so that the piston assembly may be reciprocated within the cylinder for compressing air to a desired pressure for charging the compressed air storage tank <b>104</b>. The compressor <b>112</b> further includes a head assembly <b>120</b> coupled to a boss formed in the housing <b>114</b> so as to enclose the cylinder formed therein. The head assembly <b>120</b> supplies atmospheric air to the piston assembly disposed in the compressor <b>112</b> and delivers compressed air from the piston assembly to charge the compressed air storage tank <b>104</b> via a connecting tube <b>170</b> and a check valve <b>174</b>.

Turning now to <figref idref="DRAWINGS">FIGS. 2</figref> though <b>5</b>, the head assembly <b>120</b> shown in <figref idref="DRAWINGS">FIG. 1</figref> is described. Head assembly <b>120</b> includes a housing portion <b>122</b> and a valve plate <b>124</b> that are coupled to the housing <b>114</b> of compressor <b>112</b> (see <figref idref="DRAWINGS">FIG. 1</figref>) via fasteners <b>126</b> so that the valve plate <b>124</b> is disposed between the housing portion <b>122</b> and compressor housing <b>114</b>. The head assembly <b>120</b> includes an intake cavity <b>146</b> (<figref idref="DRAWINGS">FIGS. 3 and 4</figref>) through which air generally at atmospheric pressure may enter the cylinder of compressor <b>112</b> and an exhaust cavity <b>128</b> (<figref idref="DRAWINGS">FIGS. 3 and 4</figref>) for receiving air from the cylinder that has been compressed by the piston assembly. The valve plate <b>124</b> includes one or more intake ports <b>130</b>, which allow air at atmospheric pressure to enter the cylinder of compressor <b>112</b> during intake strokes of the piston assembly. The intake ports <b>130</b> are closed (e.g., via a flapper valve or the like) during compression strokes of the piston assembly. The valve plate <b>124</b> also includes one or more exhaust ports <b>132</b>, which allow compressed air to enter the exhaust cavity <b>128</b> from the cylinder during compression strokes of the piston assembly.

In accordance with an exemplary embodiment of the present invention, the head assembly <b>120</b> may include an exhaust valve post <b>134</b> formed in housing portion <b>122</b>. In the exemplary embodiment shown in <figref idref="DRAWINGS">FIGS. 3 and 4</figref>, the exhaust valve post <b>134</b> extends from an outer wall <b>136</b> of housing portion <b>122</b> into exhaust cavity <b>128</b> and includes an inner end <b>138</b> disposed proximately to valve plate <b>124</b>. An aperture <b>140</b> is cored through the outer wall <b>136</b> of the housing portion <b>122</b> and the exhaust valve post <b>134</b> for venting the exhaust cavity <b>128</b> of the head assembly <b>120</b> prior to startup of the compressor assembly <b>102</b> (i.e., when engine or motor <b>110</b> is started to reciprocate the piston assembly of the compressor <b>112</b>). In the exemplary embodiment shown, the exhaust valve post <b>134</b> is integrally formed in the housing body <b>122</b> of the head assembly <b>120</b>. Alternately, the exhaust valve post <b>134</b> may be manufactured as a separate component and coupled to the housing body <b>122</b> using suitable fasteners such as bolts, screws, welds, or the like.

An exhaust valve assembly <b>150</b> is mounted to the valve plate <b>124</b> of head assembly <b>120</b>. The exhaust valve assembly <b>150</b> is comprised of a flapper valve <b>152</b> attached to the valve plate <b>124</b> via a suitable fastener such as rivet <b>154</b> or the like, so as to extend into exhaust cavity <b>128</b>. In the exemplary embodiment shown, the flapper valve <b>152</b> includes a first or base end <b>156</b> having an aperture <b>158</b> formed therein for receiving the rivet <b>154</b> coupling the flapper valve <b>152</b> to the valve plate <b>124</b>. One or more valve members <b>160</b> extend from the base end <b>156</b> in a generally radial fashion. Each valve member <b>160</b> includes a second end <b>162</b> coupled to the base end <b>156</b> via a flexible or resilient arm <b>164</b>. Preferably, the second end <b>162</b> of each valve member <b>160</b>, which in one embodiment, may be generally circular in shape, is disposed over a respective exhaust port <b>132</b> formed in the valve plate <b>124</b>. At least one of the valve members <b>160</b> is also positioned for engaging the end surface <b>138</b> of the exhaust valve post <b>124</b> when opened (FIG. <b>4</b>).

As shown in <figref idref="DRAWINGS">FIGS. 3 and 4</figref>, the valve member <b>160</b> that engages exhaust valve post <b>124</b> may flex between a first position, shown in <figref idref="DRAWINGS">FIG. 3</figref>, wherein the second end <b>162</b> is spaced apart from the end surface <b>138</b> of exhaust valve post <b>134</b>, and a second position, shown in <figref idref="DRAWINGS">FIG. 4</figref>, wherein the second end <b>162</b> engages the surface <b>138</b> of exhaust valve post <b>134</b> for covering the aperture <b>140</b> formed therein. In exemplary embodiments, the surface <b>138</b> of exhaust valve post <b>134</b> may be angled with respect to the valve plate <b>124</b> allowing the surface to be more fully engaged by the second end <b>162</b> of the valve member <b>160</b> to provide a better seal between the surface <b>124</b> and the second end <b>162</b>.

As shown in <figref idref="DRAWINGS">FIG. 3</figref>, the resilient arm <b>164</b> of the valve member <b>160</b> positioned to engage the exhaust valve post <b>134</b> is biased so that the second end <b>162</b> of the valve member <b>160</b> is generally spaced apart from the surface <b>138</b> of the exhaust valve post <b>134</b> during intake strokes of the compressor piston assembly or during periods when the compressor <b>120</b> is idle. In this manner, compressed air within the exhaust cavity <b>128</b> is allowed to vent through the aperture <b>140</b> formed in the exhaust valve post <b>134</b>. This venting allows the pressure within the exhaust cavity <b>128</b> to be relieved (e.g., generally reduced to atmospheric pressure) unloading the head assembly <b>120</b> to reduce the load placed on the engine or motor during startup of the compressor. During intake strokes of the piston assembly, the flapper valve <b>152</b> may further be drawn against the valve plate <b>124</b> for closing the exhaust ports <b>132</b> formed therein to prevent compressed air within the exhaust cavity <b>128</b> from being drawn back into the cylinder.

As shown in <figref idref="DRAWINGS">FIG. 4</figref>, during a compression stroke of the piston assembly of compressor <b>120</b> (FIG. <b>1</b>), air pressure within the exhaust cavity forces the second end <b>160</b> of the valve member <b>160</b> against the surface <b>138</b> of the exhaust valve post <b>134</b>, at least partially sealing or closing the aperture <b>140</b> formed therein for preventing air from being vented from the exhaust cavity <b>128</b> through the aperture <b>140</b>. In this manner, the head pressure relief assembly of the present invention eliminates the need for a switch unloader and pressure relief tube commonly used in prior air compressors. However, the head pressure relief assembly also eliminates losses in air pressure during the compression stroke of the piston assembly of the compressor <b>120</b>, greatly increasing the efficiency of the compressor <b>120</b>.

Turning now to <figref idref="DRAWINGS">FIGS. 6 and 7</figref>, the head assembly <b>120</b> shown in <figref idref="DRAWINGS">FIG. 1</figref> is described in accordance with another exemplary embodiment of the present invention. Head assembly <b>120</b> may include a housing portion <b>122</b> and a valve plate <b>124</b> that are coupled to the housing <b>114</b> of compressor <b>112</b> (see <figref idref="DRAWINGS">FIG. 1</figref>) via fasteners <b>126</b> so that the valve plate <b>124</b> is disposed between the housing portion <b>122</b> and compressor housing <b>114</b>. The head assembly <b>120</b> may include an intake cavity <b>146</b> (<figref idref="DRAWINGS">FIG. 7</figref>) through which air generally at atmospheric pressure may enter the cylinder of compressor <b>112</b> and an exhaust cavity <b>128</b> (<figref idref="DRAWINGS">FIG. 7</figref>) for receiving air from the cylinder that has been compressed by the piston assembly. The valve plate <b>124</b> may include one or more intake ports <b>130</b>, which allow air at atmospheric pressure to enter the cylinder of compressor <b>112</b> during intake strokes of the piston assembly. The intake ports <b>130</b> are closed (e.g., via a flapper valve or the like) during compression strokes of the piston assembly. The valve plate <b>124</b> also includes one or more exhaust ports <b>132</b>, which allow compressed air to enter the exhaust cavity <b>128</b> from the cylinder during compression strokes of the piston assembly.

The head assembly <b>120</b> may include an aperture <b>140</b> cored through the outer wall <b>136</b> of the housing portion <b>122</b> for venting the exhaust cavity <b>128</b> of the head assembly <b>120</b> prior to startup of the compressor assembly <b>102</b> (i.e., when engine or motor <b>110</b> is started to reciprocate the piston assembly of the compressor <b>112</b>). In this manner, compressed air within the exhaust cavity <b>128</b> is allowed to vent through the aperture <b>140</b>. This venting allows the pressure within the exhaust cavity <b>128</b> to be relieved (e.g., generally reduced to atmospheric pressure) unloading the head assembly <b>120</b> to reduce the load placed on the engine or motor during startup of the compressor. In this manner, the head pressure relief assembly of the present invention eliminates the need for a switch unloader and pressure relief tube commonly used in prior air compressors.

Turning now to <figref idref="DRAWINGS">FIG. 8</figref>, an air compressor <b>100</b> in accordance with a further exemplary embodiment of the present invention is depicted. The air compressor <b>100</b> includes a compressor assembly <b>102</b> mounted to a compressed air storage tank <b>104</b>. The compressed air storage tank <b>104</b> provides a reservoir or receiver for storing air under pressure. A spud is provided in the compressed air storage tank <b>104</b> to which a pressure manifold or pipe <b>106</b> is fitted allowing compressed air to be drawn from the tank <b>104</b> for powering air powered tools.

A pressure switch assembly <b>108</b> is mounted to the pressure manifold <b>106</b> for regulating pressure within the compressed air storage tank <b>104</b> by alternately starting and stopping the compressor assembly <b>102</b> to periodically replenish the supply of air in the tank <b>104</b>. When pressure within the tank <b>104</b> reaches a kick-in pressure, the pressure switch assembly <b>108</b> starts the compressor <b>102</b> to re-pressurize the tank <b>104</b>. As the pressure within the tank <b>104</b> reaches kick-out pressure, the pressure switch assembly <b>108</b> stops the compressor <b>102</b> to prevent over-pressurization of the tank <b>104</b>. In this manner, the pressure of the compressed air in the compressed air storage tank <b>104</b> is maintained within a range generally suitable for powering one or more air-powered tools.

The compressor assembly <b>102</b> includes an engine or motor <b>110</b> and a compressor <b>112</b> comprised of a housing <b>114</b> having a cylinder formed therein in which a piston assembly is disposed. The piston assembly is journaled to a crankshaft which couples the piston assembly to the engine or motor <b>110</b> so that the piston assembly may be reciprocated within the cylinder for compressing air to a desired pressure for charging the compressed air storage tank <b>104</b>. The compressor <b>112</b> further includes a head assembly <b>120</b> coupled to a boss formed in the housing <b>114</b> so as to enclose the cylinder formed therein. The head assembly <b>120</b> supplies atmospheric air to the piston assembly disposed in the compressor <b>112</b> and delivers compressed air from the piston assembly to charge the compressed air storage tank <b>104</b> via a connecting tube <b>170</b> and a check valve <b>174</b>.

The connecting tube <b>170</b> coupled to the head assembly <b>120</b> and the check valve <b>174</b> may include an aperture <b>172</b> cored in the connecting tube <b>170</b> for venting the exhaust cavity <b>128</b> of the head assembly <b>120</b> prior to startup of the compressor assembly <b>102</b> (i.e., when engine or motor <b>110</b> is started to reciprocate the piston assembly of the compressor <b>112</b>). In this manner, compressed air within the exhaust cavity <b>128</b> is allowed to vent through the aperture <b>172</b>. This venting allows the pressure within the exhaust cavity <b>128</b> to be relieved (e.g., generally reduced to atmospheric pressure) unloading the head assembly <b>120</b> to reduce the load placed on the engine or motor during startup of the compressor. In this manner, the head pressure relief assembly of the present invention eliminates the need for a switch unloader and pressure relief tube commonly used in prior air compressors. While the aperture <b>172</b> is shown next to the head assembly <b>120</b> in the present embodiment, one of ordinary skill in the art may contemplate coring the aperture <b>172</b> at any point between the head assembly <b>120</b> and the check valve <b>174</b>.

Turning now to <figref idref="DRAWINGS">FIG. 9</figref>, an air compressor <b>100</b> in accordance with a still further exemplary embodiment of the present invention is depicted. The air compressor <b>100</b> includes a compressor assembly <b>102</b> mounted to a compressed air storage tank <b>104</b>. The compressed air storage tank <b>104</b> provides a reservoir or receiver for storing air under pressure. A spud is provided in the compressed air storage tank <b>104</b> to which a pressure manifold or pipe <b>106</b> is fitted allowing compressed air to be drawn from the tank <b>104</b> for powering air powered tools.

A pressure switch assembly <b>108</b> is mounted to the pressure manifold <b>106</b> for regulating pressure within the compressed air storage tank <b>104</b> by alternately starting and stopping the compressor assembly <b>102</b> to periodically replenish the supply of air in the tank <b>104</b>. When pressure within the tank <b>104</b> reaches a kick-in pressure, the pressure switch assembly <b>108</b> starts the compressor <b>102</b> to re-pressurize the tank <b>104</b>. As the pressure within the tank <b>104</b> reaches kick-out pressure, the pressure switch assembly <b>108</b> stops the compressor <b>102</b> to prevent over-pressurization of the tank <b>104</b>. In this manner, the pressure of the compressed air in the compressed air storage tank <b>104</b> is maintained within a range generally suitable for powering one or more air-powered tools.

The compressor assembly <b>102</b> includes an engine or motor <b>110</b> and a compressor <b>112</b> comprised of a housing <b>114</b> having a cylinder formed therein in which a piston assembly is disposed. The piston assembly is journaled to a crankshaft which couples the piston assembly to the engine or motor <b>110</b> so that the piston assembly may be reciprocated within the cylinder for compressing air to a desired pressure for charging the compressed air storage tank <b>104</b>. The compressor <b>112</b> further includes a head assembly <b>120</b> coupled to a boss formed in the housing <b>114</b> so as to enclose the cylinder formed therein. The head assembly <b>120</b> supplies atmospheric air to the piston assembly disposed in the compressor <b>112</b> and delivers compressed air from the piston assembly to charge the compressed air storage tank <b>104</b> via a connecting tube <b>170</b> and a check valve <b>174</b>.

The check valve <b>174</b> coupled to the connecting tube <b>170</b> and the compressed air storage tank <b>104</b> may include an aperture <b>172</b> cored in the compressed air supply side of the check valve <b>174</b> for venting the exhaust cavity <b>128</b> of the head assembly <b>120</b> prior to startup of the compressor assembly <b>102</b> (i.e., when engine or motor <b>110</b> is started to reciprocate the piston assembly of the compressor <b>112</b>). In this manner, compressed air within the exhaust cavity <b>128</b> is allowed to vent through the aperture <b>172</b>. This venting allows the pressure within the exhaust cavity <b>128</b> to be relieved (e.g., generally reduced to atmospheric pressure) unloading the head assembly <b>120</b> to reduce the load placed on the engine or motor during startup of the compressor. In this manner, the head pressure relief assembly of the present invention eliminates the need for a switch unloader and pressure relief tube commonly used in prior air compressors.

Based on the foregoing description, it will be apparent to one of ordinary skill in the art that apertures (such as aperture <b>140</b>, aperture <b>172</b>) may be formed elsewhere within the head assembly <b>120</b>, the connecting tube <b>170</b>, the check valve <b>174</b>, or, alternatively in any fittings there between. Such positioning of the aperture would not depart from the scope and intent of the present invention.

It is believed that the present invention and many of its attendant advantages will be understood by the forgoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages, the form herein before described being merely an explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.